1. Field of the Invention
The invention relates generally to a cartridge that can be used, for example, to dispense single- or multi-component substances such as dental materials. The invention relates more particularly to a cartridge with at least one chamber for accommodating a substance that respectively features a dispensing opening and another opening that is closed by a piston that can be displaced in the chamber and serves for dispensing the substance, and with a piston rod mechanism for displacing the piston in the chamber.
2. Technical Background
Cartridges as described above are known for various applications, e.g., for storing and dispensing single-component or multi-component material immediately before it is processed, particularly in the field of dentistry. EP 1 679 126 A1 and EP 0 624 403 B1 respectively disclose cartridges for storing and dispensing two components, wherein a piston rod is provided that protrudes from the rear side of the cartridge.
Furthermore, TAH Industries Inc. of Robbinsville, USA, offers a cartridge of the above-mentioned type with two chambers that are arranged coaxial to and essentially behind one another and can be emptied by means of a pot-like transfer piston under the designation “u-TAH™ nano.” This cartridge is delivered with a sealing cap that needs to be removed prior to the initial use of the cartridge in order to attach, if applicable, a separate mixer or similar applicator to the cartridge. The cartridge “u-TAH™ nano” features a holding section suitable for being connected to a dispensing gun that is sold, e.g., under the designation “Centrix®” by Centrix Inc. of Shelton, USA. Such a gun is also illustrated in EP 1 256 389 A2.
This dispensing gun features a plunger that can be pushed forward into the cover of the cartridge by a defined distance such that the piston arrangement is pushed forward within the chamber in order to dispense the substances accommodated in the chambers. One peculiarity of these known cartridges can be seen in that they can be completely emptied with only one stroke of the plunger of the dispensing gun. Consequently, the plunger of the dispensing gun can be moved forward and backward by no more than the defined amount.
This type of cartridge can accommodate and dispense relatively large quantities of the substances, because the cross section of the chambers is increased for a given stroke of the plunger of the dispensing gun such that a larger quantity of the substances can be dispensed with each stroke of the plunger. However, this is perceived disadvantageous not only for optical reasons, but also because an exact metering is very difficult because a large quantity of the substance is already dispensed from the cartridge with a small stroke of the plunger. Furthermore, the force that is required for dispensing the substances and increases proportionally with the cross section, as well as the confined space conditions, for example, in the oral cavity, make it more difficult to utilize cartridges with a large cross section.
There remains a need in the art for cartridges that can accommodate and dispense larger quantities of the substances without suffering these disadvantages.